We propose a scenario for the formation of the pulsar with two white dwarfs (WDs) triple system PSR~J0337+1715 where a close binary system is tidally and frictionally destroyed inside the envelope of a massive star that later goes through an accretion induced collapse (AIC) and forms the neutron star (NS). The proposed scenario includes a new ingredient of a binary system that breaks-up inside a common envelope. One of the two lower mass stars that ends further out transfers mass to the ONeMg WD remnant of the massive star, and triggers the AIC. The inner low mass main sequence star evolves later and spins-up the NS to form a millisecond pulsar. We use the binary_c software and show that both low mass stars end as helium WDs. This scenario is not extremely sensitive to initial conditions. For example, after the low mass binary system breaks loose inside the envelope, the tertiary stellar orbit can have any eccentricity, from a circular to a very eccentric orbit; it will in any case be circularized when the tertiary star turns into a giant. In addition, the secondary star final mass is determined by its core mass during its Hertzsprung gap phase. The proposed scenario employs an efficient envelope removal by jets launched by the compact object immersed in the giant envelope, and the newly proposed grazing envelope evolution.
E. Sabach and N. Soker
Wed, 28 Jan 15